Method of joining book leaves

ABSTRACT

AN IMPROVED METHOD OF JOINING A PLURALITY OF LEVERS INTO A BOOK SECTION THROUGH THE USE OF AN ADHESIVE THREAD. THE THREAD IS TYPICALLY COATED WITH AN ADHESIVE BONDING AGENT AND IS HEATABLE BY INDIRECTLY APPLIED ENERGY. THE LEAVES ARE STITCHED TOGETHER WITH THE THREAD AFTER WHICH THE THREAD IS EXPOSED TO THE INDIRECTLY APPLIED ENERGY TO HEAT THE THREAD AND INDUCE A PERIOD OF ADHESIVENESS IN THE BONDING AGENT TO FUSE THE STRANDS OF THREAD TOGETHER AND TO THE LEAVES. A BOOK SECTION HAVINGG AN IMPROVED SEWN SEAM OR JOINT IS THUS PROVIDED.

ay 1973 w. c. HELLER, JR. -T ,7

METHOD OF JOINING BOQK LEAVES Filed Sept. 22, 1970 BY [mm/1.0 jAWzA m/ United States Patent 3,730,805 METHOD OF JOINING BOOK LEAVES William C. Heller, Jr., Milwaukee, Wis., and Leonard Shatzkin, Croton-on-Hudson, N.Y.; said Shatzkin assignor to said Heller, Jr.

Filed Sept. 22, 1970, Ser. No. 74,270 Int. Cl. 132% 19/02; B42d 1/00 US. Cl. 156-272 26 Claims ABSTRACT OF THE DISCLOSURE An improved method of joining a plurality of leaves into a book section through the use of an adhesive thread. The thread is typically coated with an adhesive bonding agent and is heatable by indirectly applied energy. The leaves are stitched together with the thread after which the thread is exposed to the indirectly applied energy to heat the thread and induce a period of adhesiveness in the bonding agent to fuse the strands of thread together and to the leaves. A book section having an improved sewn seam or joint is thus provided.

BACKGROUND OF THE INVENTION Field of the invention The present invention is directed to the book binding process and more particularly to a process for joining a plurality of leaves into a book section.

Description of the prior art A common technique for joining the sheets, or leaves, of a multi-page book is by sewing the paper or film leaves along the center fold thereof. When the number of leaves which are sewn along a common center fold exceed approximately sixteen, difficulty is encountered in having the pages lie flat when the completed book is open. For this reason, when a large number of pages are to be incorporated in the completed book, the leaves are normally separated into groups of approximately sixteen leaves termed signatures or sections. Each signature is then sewn along a center fold and to the adjacent signatures to form the body of the completed book.

In accordance with prior art processes, the leaves of the signature and the assembled signatures are sewn together with one or more strands of thread to form the book body. The aligned signatures center folds of the book body are coated with glue to lock the loose ends of the thread and to permit enough glue to seep into the sewing holes to keep the strands of thread stationary with respect to the sewing holes and the signature leaves.

It has been found that such sewing techniques are less than completely satisfactory particularly for books which receive rigorous or excessive usage, such as childrens books or library reference books. During usage of the book, individual ones of the threads may become separated from the bundle of strands, as by snagging or stretching. Or, the glue holding the strands stationary with respect to the sewing holes and signature leaves may fail due to insutficient glue or seepage thereof. Either of these conditions causes the stitches to loosen and the leaves to separate. The glue holding the thread ends locked may fail, causing the same fault. The sewing holes in the leaves may become enlarged clue to the sawing action of a tautened thread or through use of the book after the breakage of the bond between the thread and the sewing holes and signature leaves. Once the above failures arise, continued use of the book has a degenerative elfect resulting in failure of the sewn seam or joint and release of the leaves. The joint can be repaired only by completely rebinding the book to include removal of the body of the book from the case, separation of the signatures or sections, resewing the damaged signature, rebinding the signatures, and casing the assembled signatures back into the case of the book. Naturally, this is an expensive and time consuming process which could be eliminated if strong sturdy sewn joints could be obtained in the signature.

One expedient is to sew either the individual leaves or the signatures, sideways rather than along the center fold. This is commonly called side stitching. By this technique the strands of the thread are not exposed when the book is in use. While this will alleviate the problem to some extent, the user of the book must continually hold his place or the book will snap shut. This failing is particularly objectionable in childrens books since even the older child may have difiiculty in maintaining the book in the open position.

SUMMARY OF THE INVENTION It is, therefore, the object of the present invention to provide an improved method of sewing book leaves for producing strong sewn joint which may be subjected to rigorous usage without failure.

It is a further object of the present invention to provide an improved process which permits the leaves to be sewn along the center foldwhile at the same time forming sewn joints capable of withstanding hard usage.

Another object of the present invention is to provide an improved process for sewing leaves with a sturdy joint which utilizes, in so far as possible, conventional book binding techniques, thereby permitting the use of existing book binding equipment.

It is a still further object of the present invention to provide a book section having improved wear resistance properties.

Briefly, the present invention employs a thread having a period of exterior adhesiveness responsive to exposure to a selected form of indirectly applied energy. The period of adhesiveness may be thermally induced and the thread treated so as to be heatable upon exposure to the energy. To perform the process, the leaves are arranged with the portions thereof to be sewn in alignment. The leaves are sewn together at the aforesaid portions with the stitches of the treated thread. The thread is then exposed to the selected form of indirectly applied energy to heat the thread and induce the period of adhesiveness therein. The stitches of the thread become fused together to prevent the separation of the strands or freeing of the loose thread ends which has heretofore initiated failure of the sewn joint. The strands may also be bonded to the sewing holes and to the leaf portions between the holes to prevent enlargement of the holes or destruction of the leaf portions.

The thread may be formed of a material of thermally responsive adhesiveness or may be coated with a bonding agent having such properties.

In the alternative, the thread may be uncoated and the bonding agent applied to the leaves prior, or after, sewing with a heatable thread.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a book section or signature having the leaves thereof joined by stitching at the center fold in the conventional manner;

FIG. 2 is a perspective view of book body joined by side stitching;

FIG. 3 is a partially cut away perspective view of an adhesively coated and heatable thread employable in the process of the present invention;

FIG. 4 is a perspective View illustrating several steps in the process of the present invention;

FIG. 5 is a perspective view similar to FIG. 4, also illustrating several steps in the process of the present invention;

FIG. 6 is a cross sectional view taken along the center fold of a book section sewn together in accordance with the process of the present invention; and

FIG. 7 is a cross section view taken along the line 7--7 of FIG. 6 and showing the fusion of the threads and/or the leaves obtained by the process of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, there is shown therein, a book section or signature 10, sewn in the conventional manner. Signature 10 is formed of paper sheets or leaves 12 containing a center fold 14 along Which the individual leaves are joined by stitches 16 of thread 18.

The center fold portion of signature 10 is shown in greater detail in FIG. 6. As indicated in that figure, a plurality of strands 20 of thread 18 pass through holes 22 in center folds 14 of leaves 12 in a running stitch, the stitch being repeated on both sides of signature 10.

It will be appreciated that a snagging or tautening of one of strands 20 will enlarge holes 22 in leaves 12, loosening the leaves and that a loosening of the stitches of thread 18 will also loosen the leaves. Each of these conditions leads to a failure of the sewn joint.

To overcome the foregoing problem, leaves 12, either in the folded or unfolded condition, may be sewn by stitches 24 through the rear edges, i.e. side stitched, as shown in FIG. 2 so that the rear edges of the leaves are held tightly together. While, as noted supra, this will prevent loosening of the stitching or leaves, it also prevents the facile handling of leaves 12 obtained by sewing on the center fold, as shown in FIG. 1.

To overcome the aforementioned short comings of the prior art, the present invention contemplates the use of a thread 18 having a period of exterior adhesiveness responsive to exposure to a selected form of indirectly applied energy. The exposure typically results in a temperature increase so that the period of adhesiveness may be said to be thermally induced. It is also desirable that the adhesive qualities of the thread exist for only a short pe riod of time during, or after, the exposure, so that the thread is fast setting or has a short open time.

A thread of external adhesiveness may be formed, as shown in FIG. 3, by coating a twisted or braided filament 26 with an adhesively thermoplastic or thermosetting bonding agent 28. In the alternative, filament 26 may itself be selected from a substance which has the desired thermally induced adhesive qualities. The bonding agent may be applied in the liquid form or may be granular or powdered material which is affixed to filament 26. A typical bonding agent of the thermoplastic type which has been found useful for coating the filament is a water emulsion of ethylene vinyl acetate sold under the trade designation Aircoflex 400 by the Air Reduction Company of New York, N.Y. The period of adhesiveness, or open time, of such a bonding agent upon termination of the application of heat, is on the order of one second. A thermosetting bonding agent comprised of an epoxy having a cure rate proportional to temperature may be used. An uncoated but externally adhesive thread may be formed of a nylon or a polyvinyl chloride filament.

In connection with the heating properties of thread 18, by the term indirectly applied energy it is meant that the energy responsible for the temperature increases is applied through the medium of a radiant field, rather than by direct application of, for example, a heated body. Typically, the radiant fields are electric or magnetic fields. Thread 18 may be so heatable by dispersing in bonding agent 28, or impregnating in filament 26, a material 30 susceptible to heating by the indirectly applied energy. The material is preferably in the particulate form and is incorporated in the bonding agent or filament in quantities sufficient to produce the desired heating action. When added to the bonding agent or to an adhesive filament this is typically 10 to 50% by weight with respect to the bonding agent or filament. Such material, termed herein a susceptor, may be responsive to the indirect application of energy in the form of an alternating magnetic field, in which case the susceptor could consist of material heatable by induction heating, such as particles of iron oxide, preferably 'yFe O Metal or ferrite particles may also be used. The material may be responsive to an alternating electric field in which case a dielectrically heatable substance such as polyvinyl cholride may be used.

In the alternative, the filament material itself may be susceptible to heating by the indirectly applied energy. For example, a coated or uncoated filament of polyvinyl chloride may be used.

To commence the process of the present invention, leaves 12 are arranged so that the portions thereof to be sewn together are in alignment. Preferably this involves creasing each of leaves 12, at center fold 14 and then stacking the folded leaves so that the center folds are aligned along a common center fold, as shown in FIG. 1.

The stacked leaves 12 having aligned center folds are then sewn together with thread 18 in the usual manner. The sewing operation may be preceded by a drilling operation which drills holes 22 or the holes may be formed by the sewing needle. While running stitches 16 are shown in FIGS. 1 and 5, it will be appreciated that other types of stitches, such as a machine stitch, may be used, if desired. One or more strands 20 may be incorporated in each stitch 16. At the completion of the sewing, the thread 18 may be cut if only a single signature is being assembled or the sewing operation may be continued to sew other signatures and bind the assembled signatures together.

Thread 18 is then exposed to indirectly applied energy, as by inserting the common center fold 14 of leaves 12 into a radiant field. In the instance in which susceptor 30 is inductively heatable, an alternating magnetic field may be established by coils 32, shown in FIG. 4, energized by the current of alternating source 34. Coils 32 may be cooled by coolant circulated in passages 36 and may be mounted on coil supports 38 which serve as pressure platens.

Upon insertion in the field of coils 32, the susceptor 30 increases in temperature causing the thread to enter the adhesive state and commence the fusion process. During the time thread 18 is in the adhesive state, i.e. during the open time of the thread, pressure may be applied to center fold 14 by moving coil supports 38 in the direction shown by the arrows in FIG. 4. The pressure application may continue until the termination of the period of adhesiveness of thread and until the adhesive is set. In the case of thermoplastically adhesive thread, removal of center fold 14 from the field of coils 32, or the turn off of alternating current initiates the termination of the period of adhesiveness.

The exposure of threads 18 of stitches 16 to the magnetic field, and the resulting adhesive condition thereof, fuses the individual threads 18 into a unitary bundle thus preventing individual threads from being snagged or tautened. See FIG. 7. It further locks threads 18 together at each point where they cross so that the loose ends of threads 18 are secured at the points of contact with other threads.

The bonding agent 28 also tends to flow at holes 22 where the threads 18 pass through leaves 12 and acts to bond one leaf to another and threads 18 to leaves 12 at holes 22. This bonding at holes 22 acts to reduce the amount of shifting of one leaf against another which normally causes enlargement of holes 22 and loosening of stitches 16. See FIGS. 6 and 7. Bonding agent 28 also acts to reinforce the edges of holes 22 to further discourage enlargement of holes 22. Threads 18 may also be bonded to leaves 12 along center fold 14 between holes 22 to further reinforce the sewn seam.

If desired, the exposure of the thread to the applied energy may occur after formation of the book body, or even after the body is cased into the cover.

In the case in which thread 18 is subjected to dielectric heating, the center fold 14 of signature 10 may be placed in an electric field created by electrodes 40 energized by alternating current voltage source 41. Platens 38 may be incorporated in electrodes 40 as shown in FIG. 5. The remaining steps of the process proceed as described in connection with FIG. 4.

In a modification of the present invention, the bonding agent 28 may be preapplied to leaves 12 at center folds 14 prior to or after assembly of signature 10 and a heatable thread 18 for example, formed of a filament of dielectrically heatable material, used for sewing.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

We claim:

1. An improved method of joining a plurality of leaves into a book section by sewing them together, said method employing thread heatable upon exposure to a high fre quency electromagnetic field and exhibiting thermally induced exterior adhesiveness, said method comprising the steps of:

arranging the leaves with the portions thereof to be sewn together in alignment;

sewing the leaves together at the portions with stitches of the thread; and

exposing the thread to a high frequency electromagnetic field to heat the thread for fusing the thread to adjacent contacting elements to provide high strength joinder of the leaves.

2. The improved method of claim 1 wherein the thread is heatable upon exposure to a high frequency magnetic field and wherein the step of exposing the thread is further defined as exposing the thread to a high frequency magnetic field.

3. The improved method according to claim 1 wherein the thread is dielectrically heatable and wherein the step of exposing the thread is further defined as exposing the thread to a high frequency electric field.

4. The improved method according to claim 1 including an initial step of forming the thread by coating a filament with a bonding agent of thermally responsive adhesiveness and dispersing particles of a susceptor heatable upon exposure to a high frequency electromagnetic field in at least one of the bonding agent and filament.

5. The improved method according to claim 4 wherein the step of forming the thread is further defined as dispersing particles of a susceptor heatable upon exposure to a high frequency magnetic field in at least one of the bonding agent and filament.

6. The improved method according to claim wherein the step of forming the thread is further defined as dispersing particles of 'yFe O in at least one of the bonding agent and filament.

7. The improved method of claim 4 wherein the step of forming the thread is further defined as dispersing particles of a susceptor heatable upon exposure to a high frequency electric field in at least one of the bonding agent and filament.

8. The improved method according to claim 1 including an initial step of forming the thread by selecting a filament material of thermally induced exterior adhesiveness and dispersing particles of a susceptor heatable upon exposure to a high frequency electromagnetic field therein.

9. The improved method according to claim 8 wherein the step of forming the thread is further defined as dispersing particles of 'yFe O in the filament material.

10. The improved method according to claim 1 wherein the step of arranging the leaves is further defined as arranging centerfolded leaves with the centerfolds in alignment and the step sewing the leaves is further defined as securing the leaves along the centerfold.

11. The improved method according to claim 1 including the step of applying pressure to the aligned portion of the leaves at least during the termination of the fusing of the thread.

12. The improved method according to claim 4 wherein the step of forming the thread is further defined as coating the thread with a bonding agent of thermoplastic adhesiveness.

13. The improved method according to claim 4 where in the step of forming the thread is further defined as coating the thread with a bonding agent of thermosetting adhesiveness.

14. The improved method according to claim 8 further defined as selecting a filament of thermoplastic adhesiveness to form the thread.

15. An improved method of joining a plurality of leaves into a book section by sewing them together, said method employing a bonding agent having a period of thermally induced adhesiveness and a thread treated to be heatable responsive to exposure to a high frequency electromagnetic field, said method comprising the steps of arranging the leaves with a portion thereof to be sewn in alignment;

applying the bonding agent to the portions of the leaves;

sewing the aligned portions of the leaves together with strands of the thread in contact with the bonding agent; and

exposing the thread to a high frequency electromagnetic field to heat the thread and induce the period of adhesiveness in the bonding agent for fusing the strands of thread in contact with the bonding agent to provide high strength joinder of the leaves.

16. The improved method of claim 15 wherein the thread is heatable upon exposure to a high frequency magnetic field and wherein the step of exposing the thread is further defined as exposing the thread to a high frequency magnetic field.

16. The improved method according to claim 15 wherein the thread is dielectrically heatable and wherein the step of exposing the thread is further defined as exposing the thread to a high frequency electric field.

18. The improved method according to claim 15 including an initial step of forming the thread by impregnating particles of a susceptor heatable upon exposure to a high frequency electromagnetic in the thread.

19. The improved method according to claim 18 wherein the step of forming the thread is further defined as impregnating the thread with particles of a susceptor heatable upon exposure to high frequency magnetic field.

20. The improved method according to claim 5 wherein the step of forming the thread is further defined as impregnating the-thread with particles of 'yFe O 21. The improved method of claim 18 wherein the step of forming the thread is further defined as impregnating the thread with particles of a susceptor heatable upon exposure to a high frequency electric field.

22. The improved method according to claim 15 wherein the step of arranging the leaves is further defined as arranging centerfolded leaves with centerfolds in alignment and the step sewing the leaves is further defined as sewing the leaves along the centerfold.

23. The improved method according to claim 16 including the step of applying pressure to the aligned portion of the leaves at least during the terminal portion of the period of adhesiveness of the bonding agent.

24. The improved method according to claim 16 including a further initial step of selecting a bonding agent of thermoplastic adhesiveness.

25. The improved process according to claim 1 including the initial step of forming the thread by selecting a filament material which is of thermally responsive ex- 7 8 terior adhesiveness and which is heatable upon exposure 2,087,480 7/1937 Pitman 156-273 to a high frequency electromagnetic field. 2,579,488 12/1951 Freeman 156-272 26. The improved method according to claim 16 in- 2, 7, 8/1952 Wis r 156275 eluding a further initial step of selecting a bonding agent 3,560,290 2/ 1971 SeIldOl' et 2 l- 1 R of thermosetting adhsivene s 5 2,430,087 11/1947 Strittel' 93 2,769,414 11/1956 Kalmbacher et a1. 281-27 References Cited UNITED STATES PATENTS 1,972,672 9/1934 Alger 156-93 10 US. Cl. X.R. 3,234,061 2/1966 Gardner 156-93 281-27 DOUGLAS 1. DRUMMOND, Primary Examiner I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,730 Q8055 Dated May 1 1973 lnv n fl William C Heller, Jr. and Leonard Shatzkin It is certified that; error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 4 I line 9 After the word "preferably" insert --gamma-- Col. 5 line '7 After "voltage source" delete "41" and substitute --42--- Col.v 6" line Should be numbered as Claim "1?" Col. .1 line 48 After "electromagnetic" insert (Claim 18-) I ---field-- (301,6 line as Delete 16" and substitute ---l5-- (Claim'23) Col. line 69 I Delete "16" and substitute --l5--- (Claim 24) I I I Y Col. 7 line 3 I Delete "16" and substitute -l5 (Claim 26) Signed and sealed this 20th day of November 1973'.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGMEYER Attesting Officer Acting Commissioner of Patents FORM P04 050 (10-69) USCOMM-DC 60376-P69 k U. 5. GOVERNMENT PIiN TING OFFICE 1,! 0-355-334, 

